Marinette and Adrien are also very likely to be in it. Since they are the civilian identities of Ladybug and Chat Noir respectively, they could be at the beach with their friends, like Alya and Nino. Maybe Alya could be trying to get some juicy photos for the Ladyblog while at the beach.
The main characters would definitely be Marinette and Adrien. Marinette, who is Ladybug, would be a central figure as she tries to balance her normal school life during the trip with her superhero duties. And Adrien, as Chat Noir, would be there to support her and also have his own storylines, like dealing with his overbearing father's restrictions even during the trip.
Obviously, Ladybug and Chat Noir are the most likely. They already have a complex relationship, and a love potion could really stir things up between them. Marinette, as Ladybug, could be the one accidentally affected by the potion and start acting strangely around Adrien, who is Chat Noir. Another character could be Alya. She's Marinette's best friend, and she could get caught in the middle of the love - potion - induced chaos. Maybe she tries to help Marinette figure out what's wrong or even gets affected herself and falls for Nino in a more extreme way. Hawk Moth is also a candidate. He could use a love potion as part of his evil plan to manipulate Ladybug or Chat Noir.
Most likely, Ladybug and Chat Noir will be the main characters involved. Since they are the central figures in the 'Miraculous Ladybug' series, it makes sense that they would be the ones in this '7 Minutes in Heaven' scenario. They have a complex relationship filled with mystery and attraction, which would make for an interesting fanfiction.
One possible plot for a Miraculous Ladybug beach fanfiction is that Hawkmoth sends an akuma to the beach during a big surfing competition. Chat Noir is there to compete, and Ladybug has to show up and they end up having to fight the akuma while also trying to protect the civilians at the beach. They could also have some cute beach - themed banter in between the fight scenes.
Marinette and Adrien would definitely have an interesting interaction. Marinette is secretly in love with Adrien, and at a sleepover, there could be all sorts of awkward and cute moments between them. Maybe they end up in the same sleeping bag by accident. Alya and Nino could also have a great interaction. They're both best friends with Marinette and Adrien respectively, and they could be the ones planning all the fun activities for the sleepover. Another pair could be Chloe and Sabrina. Chloe might be her usual bossy self at the sleepover, and Sabrina would be following her around. But there could be a moment where Sabrina stands up to Chloe, which would be an interesting turn of events.
Obviously, Marinette and Adrien would be key characters. Marinette could be the host of the sleepover, and Adrien might show up unexpectedly, either as himself or as Chat Noir. Their interactions would be the focus, whether it's some cute and awkward moments between them.
Obviously, Ladybug and Cat Noir are the main characters. Their immortality would likely be a central focus of the story. They would be the ones experiencing the changes and challenges that come with living forever.
Ladybug and Chat Noir are definitely popular. They are the main characters in the original, so in PV fanfiction, they often take center stage. Their relationship, both as superhero partners and the potential for a romantic one, is a big draw for writers. Marinette and Adrien are also popular as their civilian identities. Writers like to explore how they balance their normal lives with their superhero duties.
Hawk Moth is another character that shows up a lot in fanfiction. Writers like to explore his motives more deeply, or come up with scenarios where he has a change of heart or forms an unexpected alliance. His complex character makes him an interesting subject for fanfiction writers to play around with.
Ladybug and Chat Noir are still the main characters. They are the ones who have to face the challenges related to the robots. There might also be new characters like the creators of the robots or people who are affected by the robotic events.